Earth-boring rotary



Dec. 16, 1930. E. E. GREVE 1,785,254

EARTH BORING ROTARY Filed April 17, 1925 Patented Dec. 16,1930

UNITED STATES PATEN T OFFICE EDGAR E. GREVE, or BELLIEVUE, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGN- ivrnnzrs, TO OIL WELL SUPPLY COMPANY; or PITTSBURGH, PENNSYLVANIA, A con,

PORATION OF NEW JERSEY EARTH-BORING 71 mm? Application filed April 17,

This invention is for a rotary for turn ing a drill in effecting earth boring operations.

Rotary drilling methods are most fre quently employed where relatively soft formations are encountered. The rotary bit,

as is well known, is carried at the end of a string of pipe which serves as a drill stem and also acts to convey water to the working M face of the bit. The pipe string is turned by a rotary, which is necessarily a relatively large heavy structure, capable of withstanding considerable loads and strains, and which is driven from a suitable engine. This rotary, when revolving, has a considerable inertia, which, with the applied power from the engine, offers an enormous resistance to any force tending to check or stop it.,

It is a very common occurrence for the drill to strike hard rock at the bottom of the hole, or to become stuck through some other cause. When this happens, the excessive force applied to the rotary causes the dr ll pipe to be twisted or broken at some polnt 111 its length.

The present invention has for its ob ect to provide some means between the rotary table and the drill pipe which w1l l act as a safety device to allow for a relative move ment between the table and the pipe when the resistance offered by the drill approaches the point where the drill pipe is liable to twist.

An embodiment of my invention s illustrated in the accompanying drawings, 1n which:

Fig. 1 is a plan view of a rotary embodying my invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is a part plan view, showing the relation which the parts assume after the drill has become stuck;

Fig. 4 is a section in the plane of hue IVIV of Fig. 1.

In the drawings, 5 designates a base having a rotary table 6 thereon which may be rotated through driving pinion 7, the table having an annular gear or gear ring for engagement with the pinion.

The table has a circular opening therein,

1923. Serial No. 632,672.

in which is a removable drive bushing 8 1 formed of'two separate parts. The drive bushing has a square hole 9 therein, through which the grief stem 10 may pass. "By reason of the shape of the grief stem and the hole in the bushing, the grief stem, and consequently, the string of l pipe 11" which it carries, is rotated with the bushing, in the usual manner nowwell understood in the art.

In the periphery ofthe bushing 'preferably attwo points, one on each member, are tangentially formed notches 12terminating in radial shoulders 13. 1

In the table at suitable points are two tangentially directed pins 14, each pin being 1 adapted to enter one of the notches'ofthe bushing. Each pin ishorizontally disposed, and is arranged to reciprocate, it being slidably supportedin the table at 15 and s'lidably supported in a centralopening 17 in aremovable plug 18 entered into'a pocket 19in the table. Each pin has a fixed collar 20 thereon which is in that portion of the pin which is in the pocket 19."A co1npression spring 21 surrounding the pin is confined between the collar and plug 18, so that the spring serves to hold the outer extremity of the pin against the shoulder 13 with which it is adapted to co-act. l i

In operation, the rotative movement of the table, the table being rotated for drilling in the direction of the arrow in Fig.1, is transmitted through springs 21 and pins 14 to the bushing 8,.so as to drive the pipestringand rotate the bit a The springs which are used are designed to transmit through the pins all the power necessary for normal drilling op erations, but their strength is such that, when the-resistance of the bit, and consequently of the drill stem and drive bushing, becomes so great as to approach the maximum torque which thepipe will safely. stand,fthey will yield. If, for instance, the bit were to suddenly strike a hard rock formation and become stuck, an abnormal load would be put on pins 14, consequently forcing. them in.- wardly against the pressure of the springs, while the rotary table would continue to turn,

until the parts had assumed the position shown in Fig. 3, when the pins would be pushed. entirely out of the notches and the strain on the pipe would thus be relieved.

The drill stem is thus protected from excessive loads and the twisting oli thereof is prevented. So far as I am aware, no means has heretofore ever been applied to a rotary drilling apparatus to prevent this twisting off of the drill stem, although it is a matter of quite common occurrence.

The invention is not restricted to the specific form of rotary shown or to the arrangement of parts as shown, as the invention may be applied to any type of rotary now in use having either a one-piece rotary table or a divided rotary table, and may be interposed at any suitable point between the pipe string or grief stem and the power driven gear ring. It is preferable, however, to interpose the safety device as close to the'pipe string as possible in order to decrease the effect of the inertia of the parts which are in rigid driving relation with the pipe, as much as possible.

I claim as my invention:

1. In a rotary drilling apparatus, the combination with a rotary table, of a drill stem, stem engaging means mounted in the table, and drill stem driving means including a spring actuated member interposed between the table and the stem engaging means for transmitting motion from the former to the latter, said member being yieldable through force applied on a line tangential to the axis of rotation of the drill stem so that said driving means will be rendered temporarily ineffective when a certain resistance of the drill stem engaging means to rotation reaches a certain point, and ineffective when the said resistance is increased.

2. A rotary drilling apparatus comprising a driven table member, a second member carried thereby through which motion may be transmitted to a drill stem, said second member having a substantially radial shoulder thereon, a reciprocable pin on the table member disposed tangentially to the axis of rotation of the latter, and a spring for resiliently holding the pin against the shoulder to provide a releasable driving connection between the two members, said releasing means operable to temporarily interrupt a rotative con nection upon a predetermined resistance being encountered.

3. An apparatus of the class described comprising a driving member, a driven memher, and means normally driving the second member from the first member yieldable through force applied on a line tangential to the axis of rotation of said driven member, to destroy the driving relation of the members upon predetermined resistance being encountered.

4. An apparatus of the class described comprising a driving member, a driven mem- EDGAR E. GREVE. 

